Wagner Alessandro Pansera

Intense rainfall events can lead to floods and related hazards, reinforcing the need for reliable design rainfall estimates. Intensity-Duration-Frequency (IDF) relationships quantify rainfall intensity across durations and return periods, yet systematic comparisons of IDF derivation methods that jointly consider multiple durations and return periods remain scarce. This study compares seven methods: two variants of the traditional procedure (TP.A; TP.B), the single-step procedure (SSP), the robust procedure (RP), the intensity transformation (IT), the third-order polynomial normal transform combined with least squares (TPNT), and the simple generalization procedure (SGP). A 40-year annual-maximum series from a pluviograph station in Porto Alegre, Brazil, was analyzed for 12 durations (5 min–24 h) and 13 return periods (2–100 years). Methods were assessed against observations using duration-specific RMSE and an overall RMSE across all duration-return-period pairs. Performance was strongly duration-dependent: fits were better at very short (5–15 min) and very long (≥ 14 h) durations, whereas short-to-intermediate durations (30 min–8 h) were consistently more challenging to represent within a single formulation. SSP showed the most consistent performance across durations, whereas TP.B showed the weakest performance. TPNT performed well at short durations but deteriorated as duration increased. TP.A showed moderate performance across durations, whereas RP, SGP, and IT had similar performance with minor duration-dependent variations. These results indicate that no single method dominates across all durations, highlighting that method selection should consider the duration range of interest, dataset characteristics, and the intended hydrological application to improve design rainfall estimates.

This study presents a comparative analysis of the performance and accuracy of predictive models for capillary absorption and water saturation in cementitious materials. Water absorption data from the literature are evaluated using formulations based on the power law, stretched exponential function, Weibull distribution, and the enhanced Terzaghi model to describe the temporal dynamics of water penetration and characterize the transport mechanisms involved. The ability of each model to represent the distinct phases of the absorption process is evaluated, with emphasis on anomalous water absorption, characterized by an initial rapid flow in capillary pores followed by a slower flow in gel pores. The distinction between these flows is essential for describing the interaction between the microstructure of cementitious materials and the evolution of absorption over time. The results provide a quantitative basis for assessing the suitability of the models in predicting the transition between absorption and saturation stages, contributing to the improvement of concrete durability modeling under real-world conditions and to the revision of technical standards. The results of the modeling and statistical analyses show that Weibull-type and stretched exponential models more accurately describe water absorption in concrete, while the square-root-of-time method produces significant errors.

In Brazil, an allocation system was implemented in 1994 to regulate the use of water, considering water availability based on the hydrological characteristics of the basins. Knowing these conditions is essential for the planning and sustainable management of water resources, thereby promoting sustainable development. The current system uses minimum reference flows to define the water availability in each basin. This study analyzed different methodologies for calculating reference flows in the Iguaçu River basin, comparing the values obtained by the FDC, AFDC, and 7-day moving averages (Q7), as well as the Weibull equation. The results indicated that the flows obtained by AFDC were higher, while the lowest flow corresponded to Q7.10. The choice between these methods has a direct impact on grant management, since the adoption of Q7.10 or Q95 imposes stricter restrictions, influencing the economy and users in the region. Therefore, defining the appropriate methodology must balance water availability and user needs.

A durabilidade do concreto armado está intrinsicamente associada à sua resistência à penetração de água e ao transporte de íons agressivos, fenômenos que podem comprometer sua integridade estrutural ao longo do tempo. O coeficiente de absorção capilar constitui um parâmetro essencial para a caracterização desse comportamento e é determinado por meio de ensaios normatizados. No entanto, a norma brasileira vigente que regulamenta esse ensaio restringe-se à descrição do procedimento experimental, sem estabelecer diretrizes para o processamento e a modelagem dos dados, o que pode dificultar a interpretação dos resultados e a extrapolação do desempenho a longo prazo. Neste estudo, foram comparados dois modelos distintos para a interpretação dos ensaios de absorção capilar. O primeiro modelo, amplamente utilizado na literatura e incorporado em normas internacionais, estabelece uma relação linear entre a absorção e a raiz quadrada do tempo. O segundo modelo, fundamentado em princípios físicos, adota uma formulação não linear que busca representar com maior precisão os mecanismos de transporte de água no concreto. Os resultados indicaram que a escolha do modelo impacta significativamente a análise dos ensaios de absorção capilar, influenciando tanto a interpretação dos dados experimentais quanto a precisão das previsões do comportamento higroscópico do concreto.

Frequency analysis of rainfall involves selecting a probabilistic model to represent sample data and perform design estimates. Various probability distributions are available for this purpose, but there is no general consensus on the most appropriate one. In Brazil, distributions such as Log-Normal, Gumbel, and Generalized Extreme Value (GEV) are commonly used, while less conventional models like Kappa (KAP) and Wakeby (WAK) require further investigation. This study provides a comparative evaluation of the Gumbel, GEV, KAP, and WAK distributions for modeling extreme precipitation events in the state of Paraná, selected for their ability to represent a broad range of rainfall data types. Additionally, an alternative methodology was applied to derive Intensity-Duration-Frequency (IDF) equations. The results demonstrate that the GEV distribution exhibited performance comparable to the WAK and KAP distributions, while outperforming the Gumbel distribution. Furthermore, the shape parameter of the GEV distribution exerted a significant effect on the accuracy of IDF relationship estimations.

Estudos de precipitação máxima têm destaque em projetos de Engenharia, vistas as perdas que suas consequências podem gerar. Instalações prediais de água pluvial captam e conduzem a água incidente na edificação à rede de drenagem. A chuva de projeto é um parâmetro de dimensionamento da instalação predial, e para obtenção de sua intensidade a NBR 10844/1989 sugere uso de dados locais de chuva; quando não há dados, a norma indica a adoção de 150 mm/h para áreas de projeção horizontal menor que 100 m². Então, o estudo estimou valores locais de intensidade de chuva a partir da distribuição Generalizada de Valores Extremos (GEV) e Momentos-LH. Foram estudados 64 postos pluviométricos da região Oeste do Paraná e seus quantis com Tr de 1, 5 e 25 anos. A desagregação de chuvas foi aplicada para obter a intensidade da chuva de duração de 5 minutos. Verificou-se que para Tr de 1 ano os valores estão abaixo de 150 mm/h, enquanto, para os demais, a maioria é superior à referência. Por fim, os resultados foram espacializados em mapas gerados pela Krigagem Ordinária. Palavras-chave: Rede de drenagem urbana. Instalações prediais. Curva IDF. Distribuição Generalizada de Valores Extremos. Momentos-LH. Krigagem Ordinária.